1. Field of the Invention
The invention relates to a coaxial plug-and-socket connector for radio frequency (RF) electrical signals, comprising a plug part and a socket part and further comprising a coupling nut for fixing the parts together.
2. Description of Relevant Art
To achieve a secure and reliable connection between the parts of coaxial connectors, coupling nuts are frequently used. Such a coupling nut is disclosed in U.S. Pat. No. 8,235,741 B2. The nut has an inner thread interfacing with an outer thread of the other connector part. Preferably, the nut is tightened by manually or by using a torque wrench to avoid excessive torque, and therefore excessive force to the connector and its contact system. If the nut is tightened with excessive torque, it may even be damaged.
An electric plug-in connector with a coupling nut is disclosed in U.S. Pat. No. 8,408,938 B2. The coupling nut is rotatable against the outer conductor of the plug connector. It has an inner thread interfacing with an outer thread of a socket part. To avoid tightening with an excessive torque, even without a torque wrench, a component is provided which is shorn off in the case of excessive torque. The disadvantage is that the connection can no more be reopened and reused.
US 2007/0145744 discloses a multi-pole connector which uses a stop ring between a union nut and a mating connector to prevent damage of a sealing element.
When tightening a coupling nut of an RF connector, there may be significant internal friction in the connector, which also causes the attached cable to rotate or at least may prevent a later rotation of the cable, if necessary. This may impose a significant mechanical tension on the cable.